The role of textural characteristics and oxygen-containing surface groups in the supercapacitor performances of activated carbons

It is suggested that the specific capacitance C0 of activated carbons at low current densities (d ∼ 1 mA cm−2) consists, to a good first approximation, of two contributions. For the H2SO4 electrolyte they correspond to approximately 0.080 F m−2 from the total accessible surface area and an additional pseudo-capacitance of 63 F mmol−1 from the surface species generating CO in thermally programmed desorption (TPD). The new correlation proposed here is an alternative to Shi's earlier approach which considered contributions from the microporous and the external surface areas. Furthermore, it appears that the variation of the specific capacitance C at high current densities d (up to 100–150 mA cm−2) depends essentially on the CO2-generating surface groups and on 1/L0, the inverse of the average micropore width.